OBSERVATIONAL CONSTRAINTS ON KICKS IN SUPERNOVAE

The absence or presence of extremely wide binaries with a radio pulsar and an optical counterpart imposes a strong constraint on the existen ce and magnitude of kicks in supernova explosions. We search for such systems by comparing the positions of radio pulsars which are not know n to be in binaries with the positions of visible stars, and find that the number of associations is negligible. According to the performed population synthesis, this implies that kicks must occur, with a lower limit of at least 10 to 20 kms-(1). The single 13-th magnitude star a t a distance of 4.9 seconds of are from the pulsar PSR B1929 + 10 is a good candidate to be the member of such a wide pair. If it turns out that this pulsar is indeed the member of a wide binary or if another w ide pair will be found in the future, the kick-velocity distribution m ust have a significant contribution from low-velocity kicks.